Rotten drunk keeps maiden in pain (7)
I believe the answer is:
torment
'pain' is the definition.
(I know that torment is a type of pain)
'rotten drunk keeps maiden' is the wordplay.
'drunk' indicates an anagram.
'keeps' is an insertion indicator.
'maiden' becomes 'm' (cricket abbreviation).
'rotten' anagrammed gives 'torent'.
'torent' enclosing 'm' is 'TORMENT'.
'in' acts as a link.
(Other definitions for torment that I've seen before include "Torture" , "Severe physical or mental suffering" , "Tease unkindly" , "Cause great pain to" , "Severe pain" .)